The present invention relates to a method of forming a catalyst structure comprising a substrate having protruding catalyst particles permanently fixed into the surface of the substrate.
Catalyst structures have been disclosed in the prior art which involve the placement of catalyst materials onto the surface of a substrate. At least one of the uses for these prior art catalytic structures is for the conversion of atmospheric ozone to molecular oxygen as well as the conversion of other airborne pollutants such as carbon monoxide and unburned hydrocarbons into harmless compounds such as carbon dioxide and water vapor. One particular use has been for the construction of automotive heat exchangers such as radiators and air conditioning condensers.
U.S. Pat. No. 4,206,083 discloses the co-precipitation of platinum, palladium and manganese oxide on a ceramic support forming a catalyst for the decomposition of ozone in air. The ceramic support is impregnated with a solution containing the precursors of the desired catalyst. The impregnated support is then dried and heated to produce platinum and palladium metal and manganese oxide.
In U.S. Pat. No. 4,343,776, an ozone abatement catalyst is described having a carrier or support of a porous refractory skeletal structure or metal monoliths of aluminum or other materials preferably having a plurality of flow-through channels. A platinum group metal and a non-precious Group VIII metal oxide or aluminate, such as an oxide or aluminate of iron, cobalt and nickel, are applied to the external surface of the carrier or support with the metal oxide or aluminate being applied with an alumina slip preferably prior to the application of the platinum group metal.
U.S. Pat. No. 5,187,137 likewise discloses an ozone decomposing catalyst comprising a manganese oxide together with palladium or palladium oxide formed as a thin film on a support. The support may be formed from various metal oxides or it may be a metal support. The catalyst is applied to the support as a thin film preferably with an alumina sol as a binder.
Another catalyst composition which is described as being adapted for ozone abatement is disclosed in U.S. Pat. No. 5,422,331. This catalytic material comprises a substrate, which may be aluminum, with an undercoat layer containing a mixture of fine particulate refractory metal oxide and a sol such as a silica sol providing good adherence to the substrate. An overlayer also contains a refractory metal oxide on which is dispersed a catalytic metal component, such as palladium and manganese components, which is then calcined.
U.S. Pat. No. 5,997,831 specifically discloses a method of treating the atmosphere to convert pollutants such as ozone, hydrocarbons and carbon monoxide to harmless compounds involving contacting the atmosphere with a heat exchanger which has an outer surface coated in selected areas with a catalytic layer. The catalyst may be manganese oxide and/or precious metals applied by dipping or spraying and the catalytic layer is coated with a porous protective coating such as a polymer.